Universal transport properties of three-dimensional topological insulator nanowires

Abstract

We report theoretical calculations of electronic and transport properties mediated by topological helical states on the walls of three-dimensional topological insulator (TI) nanowires. A universal regime of quantized conductance and fluctuations is found that is induced by disorder. The average conductance of the disordered nanowire scales as a function of the number of transmission channels $N$ in a universal form $\ensuremath{\langle}G\ensuremath{\rangle}=\ensuremath{\alpha}N+\ensuremath{\beta}$, independent of the system details. For instance, for ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ nanowires cleaved along the $x$ or $y$ direction with the quintuple layers along the $z$ direction, $\ensuremath{\langle}{G}_{xx}\ensuremath{\rangle}=(5/12)N+1/2$. The universal and quantized behavior is due to the topological physics happening on the walls of the nanowire under the influence of disorder.